This invention relates to apparatus which mixes a polymeric flocculant in dilution water and activates the polymer for liquid/solid separation, as in water and waste-water treatment, and more particularly, to polymer activation and dilution apparatus which produces more rapid and complete activation of the polymer in less processing and aging time than known apparatus, without damaging the polymer structures excessively.
Flocculants and coagulants such as polyelectrolyte materials, polymers, gums and the like ("polymers") are high molecular-weight materials used, among other things, as an aid in removing fine particles from water, for dewatering sludges, and for other liquid/solid separation applications. The polymers are tightly tangled before activation, and extend or untangle completely when fully activated in dilution water. In practice, however, the polymers do not necessarily untangle completely or fully activate, which is undesirable.
The degree to which a polymer achieves coagulation and flocculation is improved with greater polymer activation. Polymer activation can perhaps best be measured by applying an activated polymer to a substrate such as sludge or the like, and measuring the rate of settling under laboratory conditions. The highest rate of settling is indicative of the best possible polymer performance, which is believed to occur when the polymer molecules are at or reasonably close to being fully untangled or activated.
Another indication of full or optimum polymer activation is viscosity. Generally, viscosity increases as the polymer becomes more fully activated. However, the degree of potential activation is related to the chemical composition of the polymer, the chemical properties of the dilution water in which the polymer is mixed, and the manner in which the polymer is mixed with the dilution water. As a result, a particular polymer may reach a different maximum viscosity in different water or under different mixing conditions. When maximum viscosity is reached, the viscosity will not decrease significantly for a relatively long time, unless a substantial number of polymer molecules have been damaged in the activation process. By activating several samples of a particular polymer under varying time and energy conditions, optimum activation can be determined by measuring and comparing the viscosity of the samples over time. Optimum activation conditions are considered to be those conditions which produce maximum viscosity with the least amount of processing time and aging time (after processing), without a significant decrease in viscosity after the maximum viscosity is reached.
The polymer/dilution water solution can be mixed under various energy and time conditions. An inadequate combination of energy and time can result in less than complete activation, and an excessive energy and time combination can damage the polymer molecules, which is undesirable. Thus, there is a need for polymer activation apparatus which mixes the polymer with dilution water under optimum energy and time conditions, to produce more complete polymer activation.
Accordingly, an object of this invention is to provide new and improved polymer activation methods and apparatus.
Another object is to provide new and improved polymer activation methods and apparatus for water treatment.
Still another object is to provide new and improved polymer activation apparatus which produces more rapid and complete activation of the polymer in diluted polymer solutions, without excessively damaging the polymer.